Imagine a future where doctors take stem cells from your own body, grow them into cartilage in a lab and reinsert them into a joint eroded by osteoarthritis.

Or a day when physicians help your body heal itself by luring stem cells to a worn joint, where they transform into joint cartilage.

Today, such osteoarthritis treatments are only a glimmer in the eyes of researchers, who are just beginning to learn how to harness stem cells to generate joint cartilage and control inflammation in laboratories.

But for the 27 million Americans with osteoarthritis, adult stem cell research could promise amazing new treatments. Experts hope one day – perhaps in your lifetime, if you’re 50 years old – to apply these therapies and alleviate or prevent arthritis in people, as well as postpone or reduce the need for joint replacement surgery.

That day is still years away. “We’re [nowhere near] being able to put orthopedic surgeons out of work on joint replacements,” says Mary Goldring, Ph.D., professor of cell and developmental biology at Weill Cornell Medical College and senior scientist at the Hospital for Special Surgery in New York.

Most studies in the U.S. are in embryonic stages and being conducted on animals.

“We need much more evidence and research before we could recommend that a patient get such a treatment,” says Farshid Guilak, Ph.D., Laszlo Ormandy Professor of Orthopedic Surgery and director of orthopedic research at Duke University Medical Center.

Still needed are human clinical trials – rigorously controlled scientific studies conducted under the direction of the Food and Drug Administration (FDA) that are essential to test the safety and effectiveness of adult stem cell therapies – and the agency’s approval.

Some clinics already claim to offer stem cell therapies for osteoarthritis using cells harvested from a person’s own bone marrow. Published data on several hundred patients supports the promise of this emerging technology.

However, other researchers say any therapies offered now are unsafe, because they’re not tested under FDA standards. Because there’s a lack of proof about their effectiveness and potential side effects under FDA-approved study protocols, it’s best to consult your doctor about how to treat your osteoarthritis.

In fact, all the therapies have potential problems, Guilak says. For example, the stem cells could turn into an incorrect cell type or a tumor such as a teratoma, which contains tissues such as hair and bone.

But scientists are making progress into adult stem cell therapies for osteoarthritis, and some plan to start clinical trials within the next decade. Guilak, for example, hopes to start human clinical trials on laboratory-grown joint cartilage in the next five years.

What are these future osteoarthritis treatments? And how they might work? Read on for answers.

Adult Stem Cell Therapies for OsteoarthritisStem cells are the body’s master cells, found in various adult tissues, as well as embryos and umbilical cords; they can grow indefinitely and change into other types of cells. They’re a blank page, explains Rocky S. Tuan, Ph.D., director of the Center for Cellular and Molecular Engineering at the University of Pittsburgh’s School of Medicine.

“We’re just finding out what [their] jobs are,” he says.

Adult stem cells come from a patient’s own tissue, such as bone marrow and fat; they’re unlike embryonic stem cells, which are taken from embryos or umbilical cords, he says.

Think of adult stem cells as a high school student, Tuan says; they’re partially but not completely formed.

“They can take on the properties of other cells, like cartilage cells,” he explains.

Adult stem cells also have several intriguing properties, he says: They have anti-inflammatory effects, help other cells regenerate and stabilize, and protect blood vessels.

“They’re exactly what you want [for repairing damaged cartilage] because they have some ability to regulate their environment and other cells,” Tuan says.

Harvesting a patient’s own stem cells also might minimize the chances of rejection, Tuan explains.

To repair cartilage, stem cells can be taken from several places, such as bone marrow or fat cells, and then coaxed into becoming new cartilage by using growth factors, substances like proteins or steroid hormones that stimulate cell growth.

“Not all adult stem cells are the same,” Tuan says. “They keep a bit of memory of where they come from.”

Stem cells from bone marrow, for example, may have an easier time developing cartilage than those from dental pulp.

Fat cells are an especially fruitful source of adult stem cells because most people have more than they need, he says.

Here are three of the most promising approaches in adult stem cell research:

1. Laboratory-grown cartilageWho it’s for: This procedure would be used for patients with early-stage osteoarthritis, where the cartilage defects are defined but not large – “perhaps 2 centimeters,” Tuan explains.

It would also help people in their 50s and 60s who have advanced osteoarthritis and would otherwise need a joint replacement, Guilak says.

Joint replacements typically last 15-20 years, and postponing a first joint replacement reduces the likelihood of a second one; the risk of failure is much higher in a second procedure, Guilak explains.

Laboratory-grown cartilage procedure is “really a joint resurfacing that would save all the joint bone, so that a younger patient could still have a metal or plastic replacement 10-15 years later,” he says.

How it works: Surgeons measure the area of damaged joint cartilage to be replaced. Then they remove stem cells from the body and place them in a gel or material made of tiny fibers, so they can grow into a three-dimensional structure.

In about two months, the stem cells turn into cartilage, which surgeons then implant into the joint.

This process eventually could be performed with only a small incision, just large enough to insert the new cartilage structure and unfurl it over the once-damaged cartilage, Tuan predicts.

Researchers at Duke University Medical Center have attempted to grow an entire hip joint surface – about 1-1/2 inches in diameter – using adult stem cells taken primarily from dog fat cells and grown for about two weeks outside the animal. The resulting structure was then implanted in the dog.

“After we insert the structure, the animals are able to walk in about a week,” Guilak says.

“Most stem cell approaches to osteoarthritis have been trying to fill a defect, similar to filling a pothole,” he says. “This is like repaving the whole road.”

2. Stem cell insertionWho it’s for: This approach might be used with people with early joint damage, but also those with advanced osteoarthritis who have little joint cartilage left, Tuan says.

How it works: Stem cell insertion – less advanced than laboratory-grown cartilage – requires more work for researchers.

They must first harvest cells and then purify them to get usable stem cells, Tuan says.

Stem cells harvested from bone marrow, for example, include all kinds of cells – fat, connective tissue, blood vessel – so researchers must use a laser cell sorter to separate stem cells, which have specific markers.

“It’s difficult to get large numbers of purified stem cells,” Guilak explains.

Researchers then insert the stem cells into the joint, along with a material that encourages stem cells to turn into new cartilage in several months, Tuan says.

3. Stem cell recruitmentWho it’s for: This might benefit all osteoarthritis patients, whether older or younger, says Jeremy Mao, D.D.S., Ph.D., co-director of the Center for Craniofacial Regeneration at Columbia University Medical Center’s College of Dental Medicine and author of a 2010 study that used stem cell recruitment to replace missing joint cartilage in rabbits.

“But no one knows yet whether older patients will take a longer time recuperating from stem cell therapies than younger ones,” he warns.

Stem cell recruitment has one big benefit over other therapies, Dr. Mao says. Because harvesting enough stem cells can be difficult, this provides a natural supply without invading the body.

It also allows the body to heal damaged joints with the patient’s own stems cells, reducing the risk of rejection, he explains. (Cells grown outside the body and exposed to other materials, such as growth factors, could cause the immune system to reject them when they’re reinserted into the body.)

“That’s not usually an issue, however,” Guilak says.

How it works: Columbia researchers inserted a protein “that has the ability to attract the rabbit’s own stem cells into that location and regenerate cartilage,” Dr. Mao says.

Three to four weeks later, the rabbits were hopping around the lab, but it took four months for cartilage to mature fully, he says.

“When we analyzed the new [rabbit joint] cartilage, it appeared to be the same kind of cartilage as in normal tissue,” he says.

But whether stem-cell cartilage generated this way in people would have identical properties to original cartilage is unknown; it hasn’t been tested on people yet.

4. Anti-inflammatory stem cell injectionWho it’s for: Anti-inflammatory stem cell injection might benefit people at risk of developing osteoarthritis, as well as those who have the disease, says Guilak.

How it works: Guilak and his team have studied the effects of injecting purified stem cells into the damaged knee joints of mice.

“The stem cells prevented osteoarthritis in the joints,” Guilak says. “It appears that they reduce the degenerative process and inflammation.”

He’s excited because it’s a very different use of adult stem cells than growing a new cartilage.

“It’s more like the stem cells are an automatic drug delivery system,” he says.

Based on his studies, Guilak says purified stem cells have the best anti-inflammatory effect.

Hopes and DrawbacksMany questions remain about stem cell therapies for osteoarthritis patients, including their efficacy in people and how much they’ll cost.

“The [therapies] have to be economically viable so they can be used in as many patients as possible,” Dr. Mao says.

To keep up on stem cell research or to find out about human clinical trials when they become available, go to clinicaltrials.gov and type in “stem cells and osteoarthritis.” (Find out more about clinical trials here.)

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